Pore structure of macroporous monolithic cryogels prepared from poly(vinyl alcohol)

Abstract

Macroporous monolithic cryogels made from poly(vinyl alcohol) (PVA) with degree of saponification 87.7% have been prepared using a crosslinking reaction with glutaraldehyde under acidic conditions at subzero temperatures. The porous structure of the monolithic cryogels from PVA (cryoPVA), analyzed using optical microscopy, scanning electron microscopy, and environmental scanning electron microscopy, revealed interconnected macropores up to 150 m in size with a noticeable microporosity of the gel walls. Differential scanning calorimetry measurement showed that more than 90% of the water in the cryoPVA monoliths was freezable water, while the amount of polymer bound water increased with increase in the polymer concentration in the cryoPVA sample. The swelling degree of cryoPVA depended on concentration of polymer in the initial reaction mixture and degree of crosslinking. The cryoPVA monoliths were elastic and spongy-like materials that can be dried, stored in dried state, and re-swelled when required. Derivatization of hydroxyl-groups of the cryoPVA monolith allowed incorporation of required functionality. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1057-1066, 200

Macroporous gels prepared at subzero temperatures as novel materials for chromatography of particulate‐containing fluids and cell culture applications

“…The MGs with elastic and sponge-like morphology, prepared from low [9,10,13,14] and high molecular weight [15 -17] precursors, are produced mainly through free-radical polymerization reaction in an aqueous medium at subzero temperatures. Some examples of MGs with sponge-like morphology are those based on polyacrylamide (pAAm) [9,18], poly(dimethyl acrylamide) (pDMAA) [19], poly(hydroxyethyl methacrylate) (pHEMA) [14], polyethylene glycol (PEG) [14], dextran-methacrylate [16], and PVA (with DH less than 90%) [15] (Table 1). These MGs are designed as monolithic rods, discs, and sheets.…”

Removal of endocrine‐disrupting compounds from water using macroporous molecularly imprinted cryogels in a moving‐bed reactor

“…The plain PVA cryogels were prepared using solution of PVA 4.5% w/v as described by Plieva et al [21]. The composite MIP(NIP)/MGPs were prepared as follows: the MIP (NIP) particles (1.8 g) were mixed with the PVA solution (4.5%, w/v, with pH 1.2, 40 mL) and the suspension was stirred for 5 min in an ice bath.…”

“…SEM was performed as described by Plieva et al [21]. The resistance of MIP(NIP)/MGP to attrition was estimated as loss of weight by MIP(NIP)/MGPs due to continuous stirring at 400 rpm for 48 h.…”

“…These MIP particles were used for the preparation of selective adsorption medium consisting of poly(vinyl alcohol) (PVA) cryogels embedded with MIP (or NIP) particles and formed inside the plastic Kaldnes carriers (MIP(NIP)/MGPs). The PVA cryogels have been shown to have excellent flowthrough properties when prepared as monolithic columns [21] or when designed as a composite selective monolithic medium [17]. The prepared selective adsorption media (E2-MIP/MGPs, atrazine-MIP/MGPs and NP-MIP/MGPs) were evaluated on removal of the contaminants (E2, atrazine and NP, respectively) from water and compared to the respective nonselective media (NIP/ MGPs).…”

Synthesis of Polymer Sensor for Detection of Phosphate in Water

“…Chemical cross-linking can be conducted by irradiation or the use of bifunctional cross-linkers, while physical cross-linking can be achieved by the use of freezing/thawing cycles to form crystals. The combination of the two methods of synthesis produces an elastic and sponge-like cryogel with good mechanical stability and high flow-through pores [20], [21].…”